contrib; dracut: centralise root= parsing, actually support root=s

So far, everything parsed root= manually, which meant that while
zfs-parse.sh was updated, and supposedly supported + -> ' ' conversion,
it meant nothing

Instead, centralise parsing, and allow:
  root=
  root=zfs
  root=zfs:
  root=zfs:AUTO

  root=ZFS=data/set
  root=zfs:data/set
  root=zfs:ZFS=data/set (as a side-effect; allowed but undocumented)

  rootfstype=zfs AND root=data/set <=> root=data/set
  rootfstype=zfs AND root=         <=> root=zfs:AUTO

So rootfstype=zfs /also/ behaves as expected, and + decoding works

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #13291

contrib/dracut/90zfs/mount-zfs.sh.in

@@ -3,34 +3,20 @@
 
 . /lib/dracut-zfs-lib.sh
 
-ZFS_DATASET=""
+decode_root_args || return 0
-ZFS_POOL=""
-
-case "${root}" in
-	zfs:*) ;;
-	*) return ;;
-esac
 
 GENERATOR_FILE=/run/systemd/generator/sysroot.mount
 GENERATOR_EXTENSION=/run/systemd/generator/sysroot.mount.d/zfs-enhancement.conf
 
 if [ -e "$GENERATOR_FILE" ] && [ -e "$GENERATOR_EXTENSION" ]; then
-	# If the ZFS sysroot.mount flag exists, the initial RAM disk configured
+	# We're under systemd and dracut-zfs-generator ran to completion.
-	# it to mount ZFS on root.  In that case, we bail early.  This flag
+	info "ZFS: Delegating root mount to sysroot.mount at al."
-	# file gets created by the zfs-generator program upon successful run.
+
-	info "ZFS: There is a sysroot.mount and zfs-generator has extended it."
-	info "ZFS: Delegating root mount to sysroot.mount."
-	# Let us tell the initrd to run on shutdown.
-	# We have a shutdown hook to run
-	# because we imported the pool.
 	# We now prevent Dracut from running this thing again.
-	for zfsmounthook in "$hookdir"/mount/*zfs* ; do
+	rm -f "$hookdir"/mount/*zfs*
-		if [ -f "$zfsmounthook" ] ; then
-			rm -f "$zfsmounthook"
-		fi
-	done
 	return
 fi
+
 info "ZFS: No sysroot.mount exists or zfs-generator did not extend it."
 info "ZFS: Mounting root with the traditional mount-zfs.sh instead."
 
@@ -38,6 +24,9 @@ info "ZFS: Mounting root with the traditional mount-zfs.sh instead."
 modprobe zfs 2>/dev/null
 udevadm settle
 
+ZFS_DATASET=
+ZFS_POOL=
+
 if [ "${root}" = "zfs:AUTO" ] ; then
 	if ! ZFS_DATASET="$(find_bootfs)" ; then
 		# shellcheck disable=SC2086
@@ -53,7 +42,7 @@ if [ "${root}" = "zfs:AUTO" ] ; then
 	info "ZFS: Using ${ZFS_DATASET} as root."
 fi
 
-ZFS_DATASET="${ZFS_DATASET:-${root#zfs:}}"
+ZFS_DATASET="${ZFS_DATASET:-${root}}"
 ZFS_POOL="${ZFS_DATASET%%/*}"
 
 if import_pool "${ZFS_POOL}" ; then

contrib/dracut/90zfs/parse-zfs.sh.in

@@ -1,7 +1,8 @@
 #!/bin/sh
 # shellcheck disable=SC2034,SC2154
 
-. /lib/dracut-lib.sh
+# shellcheck source=zfs-lib.sh.in
+. /lib/dracut-zfs-lib.sh
 
 # Let the command line override our host id.
 spl_hostid=$(getarg spl_hostid=)
@@ -15,46 +16,20 @@ else
 	warn "ZFS: Pools may not import correctly."
 fi
 
-wait_for_zfs=0
+if decode_root_args; then
-case "${root}" in
+	if [ "$root" = "zfs:AUTO" ]; then
-	""|zfs|zfs:)
+		info "ZFS: Boot dataset autodetected from bootfs=."
-		# We'll take root unset, root=zfs, or root=zfs:
+	else
-		# No root set, so we want to read the bootfs attribute.  We
+		info "ZFS: Boot dataset is ${root}."
-		# can't do that until udev settles so we'll set dummy values
+	fi
-		# and hope for the best later on.
+
-		root="zfs:AUTO"
 	rootok=1
-		wait_for_zfs=1
-
-		info "ZFS: Enabling autodetection of bootfs after udev settles."
-		;;
-
-	ZFS=*|zfs:*)
-		# root is explicit ZFS root.  Parse it now.  We can handle
-		# a root=... param in any of the following formats:
-		# root=ZFS=rpool/ROOT
-		# root=zfs:rpool/ROOT
-		# root=ZFS=pool+with+space/ROOT+WITH+SPACE (translates to root=ZFS=pool with space/ROOT WITH SPACE)
-
-		# Strip down to just the pool/fs
-		root="${root#zfs:}"
-		root="zfs:${root#ZFS=}"
-		# switch + with spaces because kernel cmdline does not allow us to quote parameters
-		root=$(echo "$root" | tr '+' ' ')
-		rootok=1
-		wait_for_zfs=1
-
-		info "ZFS: Set ${root} as bootfs."
-		;;
-
-	*)
-		info "ZFS: no ZFS-on-root"
-esac
-
 	# Make sure Dracut is happy that we have a root and will wait for ZFS
 	# modules to settle before mounting.
-if [ "${wait_for_zfs}" -eq 1 ]; then
+	if [ -n "${wait_for_zfs}" ]; then
-	ln -s /dev/null /dev/root 2>/dev/null
+		ln -s null /dev/root
-	initqueuedir="${hookdir}/initqueue/finished"
+		echo '[ -e /dev/zfs ]' > "${hookdir}/initqueue/finished/zfs.sh"
-	echo '[ -e /dev/zfs ]' > "${initqueuedir}/zfs.sh"
+	fi
+else
+	info "ZFS: no ZFS-on-root."
 fi

contrib/dracut/90zfs/zfs-generator.sh.in

@@ -1,5 +1,5 @@
 #!/bin/sh
-# shellcheck disable=SC2016,SC1004
+# shellcheck disable=SC2016,SC1004,SC2154
 
 grep -wq debug /proc/cmdline && debug=1
 [ -n "$debug" ] && echo "zfs-generator: starting" >> /dev/kmsg
@@ -10,37 +10,17 @@ GENERATOR_DIR="$1"
     exit 1
 }
 
-[ -f /lib/dracut-lib.sh ] && dracutlib=/lib/dracut-lib.sh
+# shellcheck source=zfs-lib.sh.in
-[ -f /usr/lib/dracut/modules.d/99base/dracut-lib.sh ] && dracutlib=/usr/lib/dracut/modules.d/99base/dracut-lib.sh
-command -v getarg >/dev/null 2>&1 || {
-    [ -n "$debug" ] && echo "zfs-generator: loading Dracut library from $dracutlib" >> /dev/kmsg
-    . "$dracutlib"
-}
-
 . /lib/dracut-zfs-lib.sh
+decode_root_args || exit 0
 
-[ -z "$root" ]       && root=$(getarg root=)
+[ -z "${rootflags}" ] && rootflags=$(getarg rootflags=)
-[ -z "$rootfstype" ] && rootfstype=$(getarg rootfstype=)
-[ -z "$rootflags" ]  && rootflags=$(getarg rootflags=)
-
-# If root is not ZFS= or zfs: or rootfstype is not zfs
-# then we are not supposed to handle it.
-[ "${root##zfs:}" = "${root}" ] &&
-	[ "${root##ZFS=}" = "${root}" ] &&
-	[ "$rootfstype" != "zfs" ] &&
-	exit 0
-
 case ",${rootflags}," in
 	*,zfsutil,*) ;;
 	,,)	rootflags=zfsutil ;;
 	*)	rootflags="zfsutil,${rootflags}" ;;
 esac
 
-if [ "${root}" != "zfs:AUTO" ]; then
-  root="${root##zfs:}"
-  root="${root##ZFS=}"
-fi
-
 [ -n "$debug" ] && echo "zfs-generator: writing extension for sysroot.mount to $GENERATOR_DIR/sysroot.mount.d/zfs-enhancement.conf" >> /dev/kmsg
 
 
@@ -89,7 +69,7 @@ else
   _zfs_generator_cb() {
       dset="${1}"
       mpnt="${2}"
-      unit="sysroot$(echo "$mpnt" | tr '/' '-').mount"
+      unit="$(systemd-escape --suffix=mount -p "/sysroot${mpnt}")"
 
       {
           echo "[Unit]"

contrib/dracut/90zfs/zfs-lib.sh.in

@@ -1,6 +1,6 @@
 #!/bin/sh
 
-command -v getarg >/dev/null || . /lib/dracut-lib.sh
+command -v getarg >/dev/null || . /lib/dracut-lib.sh || . /usr/lib/dracut/modules.d/99base/dracut-lib.sh
 command -v getargbool >/dev/null || {
     # Compatibility with older Dracut versions.
     # With apologies to the Dracut developers.
@@ -161,7 +161,9 @@ ask_for_password() {
         shift
     done
 
-    { flock -s 9;
+    {
+        flock -s 9
+
         # Prompt for password with plymouth, if installed and running.
         if plymouth --ping 2>/dev/null; then
             plymouth ask-for-password \
@@ -191,3 +193,58 @@ ask_for_password() {
     [ "$ret" -ne 0 ] && echo "Wrong password" >&2
     return "$ret"
 }
+
+# Parse root=, rootfstype=, return them decoded and normalised to zfs:AUTO for auto, plain dset for explicit
+#
+# True if ZFS-on-root, false if we shouldn't
+#
+# Supported values:
+#   root=
+#   root=zfs
+#   root=zfs:
+#   root=zfs:AUTO
+#
+#   root=ZFS=data/set
+#   root=zfs:data/set
+#   root=zfs:ZFS=data/set (as a side-effect; allowed but undocumented)
+#
+#   rootfstype=zfs AND root=data/set <=> root=data/set
+#   rootfstype=zfs AND root=         <=> root=zfs:AUTO
+#
+# '+'es in explicit dataset decoded to ' 's.
+decode_root_args() {
+    if [ -n "$rootfstype" ]; then
+        [ "$rootfstype" = zfs ]
+        return
+    fi
+
+    root=$(getarg root=)
+    rootfstype=$(getarg rootfstype=)
+
+    # shellcheck disable=SC2249
+    case "$root" in
+        ""|zfs|zfs:|zfs:AUTO)
+            root=zfs:AUTO
+            rootfstype=zfs
+            return 0
+            ;;
+
+        ZFS=*|zfs:*)
+            root="${root#zfs:}"
+            root="${root#ZFS=}"
+            root=$(echo "$root" | tr '+' ' ')
+            rootfstype=zfs
+            return 0
+            ;;
+    esac
+
+    if [ "$rootfstype" = "zfs" ]; then
+        case "$root" in
+            "") root=zfs:AUTO ;;
+            *)  root=$(echo "$root" | tr '+' ' ') ;;
+        esac
+        return 0
+    fi
+
+    return 1
+}

contrib/dracut/90zfs/zfs-load-key.sh.in

@@ -4,32 +4,20 @@
 # only run this on systemd systems, we handle the decrypt in mount-zfs.sh in the mount hook otherwise
 [ -e /bin/systemctl ] || [ -e /usr/bin/systemctl ] || return 0
 
-# This script only gets executed on systemd systems, see mount-zfs.sh for non-systemd systems
+# shellcheck source=zfs-lib.sh.in
+. /lib/dracut-zfs-lib.sh
 
-# import the libs now that we know the pool imported
+decode_root_args || return 0
-[ -f /lib/dracut-lib.sh ] && dracutlib=/lib/dracut-lib.sh
-[ -f /usr/lib/dracut/modules.d/99base/dracut-lib.sh ] && dracutlib=/usr/lib/dracut/modules.d/99base/dracut-lib.sh
-# shellcheck source=./lib-zfs.sh.in
-. "$dracutlib"
-
-# load the kernel command line vars
-[ -z "$root" ] && root="$(getarg root=)"
-# If root is not ZFS= or zfs: or rootfstype is not zfs then we are not supposed to handle it.
-[ "${root##zfs:}" = "${root}" ] && [ "${root##ZFS=}" = "${root}" ] && [ "$rootfstype" != "zfs" ] && exit 0
 
 # There is a race between the zpool import and the pre-mount hooks, so we wait for a pool to be imported
-while [ "$(zpool list -H)" = "" ]; do
+while ! systemctl is-active --quiet zfs-import.target; do
-    systemctl is-failed --quiet zfs-import-cache.service zfs-import-scan.service && exit 1
+    systemctl is-failed --quiet zfs-import-cache.service zfs-import-scan.service && return 1
     sleep 0.1s
 done
 
-# run this after import as zfs-import-cache/scan service is confirmed good
+BOOTFS="$root"
-# we do not overwrite the ${root} variable, but create a new one, BOOTFS, to hold the dataset
+if [ "$BOOTFS" = "zfs:AUTO" ]; then
-if [ "${root}" = "zfs:AUTO" ] ; then
+    BOOTFS="$(zpool get -Ho value bootfs | grep -m1 -vFx -)"
-    BOOTFS="$(zpool list -H -o bootfs | awk '$1 != "-" {print; exit}')"
-else
-    BOOTFS="${root##zfs:}"
-    BOOTFS="${BOOTFS##ZFS=}"
 fi
 
 # if pool encryption is active and the zfs command understands '-o encryption'

contrib/dracut/README.md

@@ -16,18 +16,18 @@ Encrypted datasets have keys loaded automatically or prompted for.
 If the root dataset contains children with `mountpoint=`s of `/etc`, `/bin`, `/lib*`, or `/usr`, they're mounted too.
 
 ## cmdline
-1. `root=`            | Root dataset is…                                         | Pools imported |
+1. `root=`                    | Root dataset is…                                         |
-   -------------------|----------------------------------------------------------|----------------|
+   ---------------------------|----------------------------------------------------------|
-   *(empty)*          | the first `bootfs=` after `zpool import -aN`             | all            |
+   *(empty)*                  | the first `bootfs=` after `zpool import -aN`             |
-   `zfs:AUTO`         | *(as above, but overriding other autoselection methods)* | all            |
+   `zfs:AUTO`, `zfs:`, `zfs`  | *(as above, but overriding other autoselection methods)* |
-   `ZFS=pool/dataset` | `pool/dataset`                                           | `pool`         |
+   `ZFS=pool/dataset`         | `pool/dataset`                                           |
-   `zfs:pool/dataset` | *(as above)*                                             | `pool`         |
+   `zfs:pool/dataset`         | *(as above)*                                             |
 
    All `+`es are replaced with spaces (i.e. to boot from `root pool/data set`, pass `root=zfs:root+pool/data+set`).
 
    The dataset can be at any depth, including being the pool's root dataset (i.e. `root=zfs:pool`).
 
-   `rootfstype=zfs` is mostly equivalent to `root=zfs:AUTO`.
+   `rootfstype=zfs` is equivalent to `root=zfs:AUTO`, `rootfstype=zfs root=pool/dataset` is equivalent to `root=zfs:pool/dataset`.
 
 2. `spl_hostid`: passed to `zgenhostid -f`, useful to override the `/etc/hostid` file baked into the initrd.